MADISON, Wis. (AP) — A 13-year-old boy who had researched school shootings online was arrested hours after he tried to enter a Wisconsin elementary school with suspicious bags, police said.

Investigators believe the boy was armed, judging by videos of him brandishing what investigators believe was a rifle and comments he made to other students, said Patrick Patton, police chief in Kenosha, a city on Lake Michigan between Milwaukee and Chicago.

“We narrowly missed a tragedy,” Patton said at a news conference Thursday afternoon.

The teen tried to enter Roosevelt Elementary School around 9 a.m. Thursday with a backpack and a duffle bag, according to police. Staff members grew suspicious and moved to question him, but he fled.

Kenosha Unified schools were placed on lockdown for the rest of the day as police searched for the boy. They finally arrested him at his home that afternoon.

The teen attends Mahone Middle School in Kenosha and was a former Roosevelt Elementary student, police said, but they have not released his name. They said in a news release Friday that he has been charged with making terroristic threats. Kenosha County District Attorney Michael Graveley said in an email to The Associated Press on Friday that the boy will be prosecuted in juvenile court, where proceedings are confidential.

It was unclear Friday whether the boy was actually armed when he tried to enter the elementary school. Patton said investigators believe he was carrying a firearm, but the chief has not said whether police recovered any weapons or ammunition from him.

A search of his home netted several pellet guns that resembled real handguns and a pellet rifle that resembled a real rifle, police said in Friday’s news release. The boy’s mother told investigators he didn’t have access to any actual firearms.

The teen told detectives he went to the elementary school to sell candy but later told a social worker he intended to scare students, police said.

Investigators also “have information that the suspect performed multiple internet searches related to school shootings,” Patton said Thursday, adding that the teen had shared videos and made several comments to fellow students for weeks before Thursday.

“This is something that had been told to people of his growing intentions,” Patton said. “We know that there is internet searches, and all the red flags that we would look for and expect someone to report were there.”

Police received at least one video of the student wielding what investigators believe is a rifle, Patton said. The chief played a video at a news conference Thursday that shows the student holding a firearm as he appears to practice room-entry techniques, Patton said. The chief did not specify when or where the video was filmed, but it appears to have been filmed in a home.

“The Kenosha Police Department had reason to believe the suspect had access to some type of firearm based on videos on social media and other witness information,” the agency said in Friday’s news release. “The actions on scene were extremely suspicious and the internet activity by the suspect suggested they had extensive research history related to previous school shootings, information on how to execute a school shooting, and specifics about the targeted building.”

The student was taken into custody some six months after police shot and killed an armed student outside a Wisconsin middle school following a report of someone with a weapon. The May shooting in Mount Horeb, outside Madison, sent children fleeing and led to an hourslong lockdown of local schools. Prosecutors announced in August that the officers who fatally shot the student would not face criminal charges.

Kenosha made national headlines in August 2020 after a white police officer shot a Black man during a domestic disturbance, leaving him paralyzed. The shooting spurred several nights of protests. A white Illinois teenager named Kyle Rittenhouse shot three people during the unrest, killing two of them. A jury eventually acquitted Rittenhouse of any wrongdoing after he argued he fired in self-defense.